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青藏高原雨季特征量的气候特征及其南北差异

Rainy Season Characteristics and Spatial Pattern over the Qinghai-Xizang Plateau

  • 摘要: 利用1980~2019年青藏高原101个气象观测站的逐日降水量和气温数据,参考《中国雨季监测指标》,计算了雨季特征量(包括雨季开始期、结束期、持续时间、降水量和降水强度),分析了青藏高原雨季特征量的气候特征,并讨论了雨季特征量的区域差异。结果表明:(1)青藏高原雨季开始期最早(晚)为5月2日(6月19日),由高原东部向西部逐渐推进;结束期最早(晚)为9月15日(10月20日),由高原西部向东部快速结束;青藏高原东部(西部)雨季持续时间超过5个月(不足3个月)。(2)青藏高原雨季开始期与持续时间的年际变化幅度空间分布特征基本一致,其中,藏东南和柴达木盆地变化幅度较大;雨季结束期(降水量)的变化幅度明显偏小(大),雨季结束期变化幅度大(小)值区与降水量变化幅度小(大)值区相对应。(3)相比于雨季结束期,开始期与持续时间和降水量的关系更为密切,即雨季开始期早(晚)对应雨季持续时间长(短)和雨季降水量多(少)。(4)青藏高原雨季各特征量主要以唐古拉山(32.5° N)为界,呈现出南北反相的空间分布特征。相对于北部,南部雨季开始偏晚,结束早,持续时间短,降水量偏多、降水强度偏强。

     

    Abstract: Under global warming, the climatic features of the rainy season are crucial to understanding the regional water cycle. Based on daily meteorological data from 101 sites over the Qinghai-Xizang Plateau from 1980 to 2019, we investigate climatic features in the rainy season, including the onset and end dates, duration, precipitation amount, and precipitation intensity, which is refered to the “China Rainy Season Monitoring Indicators—Rainy Season in Southwest”. The climatic characteristics of these factors and their regional differences were also analyzed. The following results were found: (1) The earliest (latest) onset of the rainy season over the Qinghai-Xizang Plateau is 2 May (19 June), gradually extending from east to west. The earliest (latest) end date of the rainy season is15 September (20 October), quickly ending from west to east, while the rainy season lasts for more than five months (less than three months) in the eastern (western) Qinghai-Xizang Plateau. (2) The interannual variations of onset dates and duration of the rainy season over the Qinghai-Xizang Plateau show a consistent spatial pattern, with relatively high values in the southeastern Qinghai-Xizang Plateau and Qaidam Basin. The interannual variation in the end dates of the rainy season is significantly small and that of precipitation is large, with the coincidence of the small former and the large later. (3) The onset date of the rainy season is more closely connected to its duration and precipitation amounts than to the end date. Specifically, an early (late) onset of the rainy season corresponds to a longer (shorter) duration and a higher (lower) precipitation amount. (4) The spatial pattern of rainy season over the Qinghai-Xizang Plateau features significantly north−south reverse, which is divided by the Tanggula Mountains (32.5° N). The south Qinghai-Xizang Plateau presents a later onset date, an earlier end date, a shorter duration, higher precipitation amounts, and greater precipitation intensity than that on the north Qinghai-Xizang Plateau.

     

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